Does anyone know the size socket I will need for the bolt on the tongue? I borrowed a friend's impact wrench. I tried to put one of my socket's on there but it was too small and only goes up to 7/8", so I am guessing it is between 1"-1.25", but I would like to know and just go buy that size socket to make use of the impact. I can get a whole set for about $25 at Harbor Freight, but they do not sell the individual size I need, I don't believe.

How about just measuring the bolt? If you have a Sears store, I believe they sell individual impact sockets. Be sure to us an impact socket as hardened sockets can break under pressure.

Does anyone know the size socket I will need for the bolt on the tongue? I borrowed a friend's impact wrench. I tried to put one of my socket's on there but it was too small and only goes up to 7/8", so I am guessing it is between 1"-1.25", but I would like to know and just go buy that size socket to make use of the impact. I can get a whole set for about $25 at Harbor Freight, but they do not sell the individual size I need, I don't believe.

I'm pretty sure you'll need a 15/16" socket. Yours MAY be different so I can't say for sure. Just going by memory. My boat is normally right here in my driveway, but I just took it to storage for the week so I can't even check mine right now.

I'm with Peter... get an impact socket from Sears, although the whole set from Harbour Freight may be the same cost. Usually Sears will let you exchange it if it hasn't been used if you explain you got the wrong size. And with a black impact socket, you'll know if it's been used.

If your bolt is stuck like mine was, be prepared to start cussin' at that 1/2" impact (assuming your friend loaned you a 1/2" drive).

I know you indicated that you didn't want to take a torch to your trailer for fear of damaging the paint. How about going the other way? Getting the bolt/pin as cold as possible will actually make the bolt marginally smaller. If you have a source for a little dry-ice, try getting the dry-ice on the pin/bolt (duct tape it to it, the dry-ice will evaporate and you can get started). Make sure you don't touch the surrounding metal since it will get quite cold and will "attach" your finger to the pin/bolt.
That, along with the impact wrench (or a breaker-bar with a 2 foot pipe and then a 4' crow bar out the other end of the pipe) might be enough. I know that removing Front Wheel drive Axle nuts is a bear, and I have to use the "breaker bar/pipe/crowbar trick" (you HAVE to use a impact socket, you'll break any normal socket putting that much force on it.
Not sure if the "cold trick" will work here. I use it all the time, whenever I'm going to press anything in (Ball joints for upper/lower control arms, etc.) I put those in the freezer the night before, makes the press process much easier. You know, shrinkage...